Purely orbital diamagnetic to paramagnetic fluctuation of quasi two-dimensional carriers under in-plane magnetic field

TL;DR

This paper investigates how in-plane magnetic fields induce orbital diamagnetic to paramagnetic fluctuations in quasi-two-dimensional carriers, revealing non-linear magnetization behavior and fluctuation phenomena in double quantum wells.

Contribution

It introduces a self-consistent numerical approach to analyze magnetic response in quasi-2D systems under in-plane fields, highlighting orbital fluctuation phenomena not previously characterized.

Findings

Magnetization $M$ opposes the magnetic field $H$ but exhibits non-linear behavior.

The derivative $rac{ ext{d}M}{ ext{d}H}$ fluctuates between negative and positive.

Orbital diamagnetic to paramagnetic fluctuation is predicted in the system.

Abstract

An external magnetic field, $H$, applied parallel to a quasi two-dimensional system modifies quantitatively and qualitatively the density of states. Using a self-consistent numerical approach, we study how this affects the entropy, $S$, the free energy, $F$, and the magnetization, $M$, for different sheet carrier concentrations, $N_s$. As a prototype system we employ III-V double quantum wells. We find that although $M$ is mainly in the opposite direction of $H$, the system is not linear. Surprisingly $\partial M / \partial H$ swings between negative and positive values, i.e., we predict an entirely orbital diamagnetic to paramagnetic fluctuation. This phenomenon is important compared to the ideal de Haas-van Alphen effect i.e. the corresponding phenomenon under perpendicular magnetic field.